vfio: Don't cache MSIMessage

Commit 40509f7 added a test to avoid updating KVM MSI routes when the
MSIMessage is unchanged and f4d45d4 switched to relying on this
rather than doing our own comparison.  Our cached msg is effectively
unused now.  Remove it.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/misc/vfio.c

@@ -132,7 +132,6 @@ typedef struct VFIOMSIVector {
     EventNotifier interrupt;
     EventNotifier kvm_interrupt;
     struct VFIODevice *vdev; /* back pointer to device */
-    MSIMessage msg; /* cache the MSI message so we know when it changes */
     int virq;
     bool use;
 } VFIOMSIVector;
@@ -744,7 +743,6 @@ static void vfio_add_kvm_msi_virq(VFIOMSIVector *vector, MSIMessage *msg,
         return;
     }
 
-    vector->msg = *msg;
     vector->virq = virq;
 }
 
@@ -760,7 +758,6 @@ static void vfio_remove_kvm_msi_virq(VFIOMSIVector *vector)
 static void vfio_update_kvm_msi_virq(VFIOMSIVector *vector, MSIMessage msg)
 {
     kvm_irqchip_update_msi_route(kvm_state, vector->virq, msg);
-    vector->msg = msg;
 }
 
 static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr,
@@ -939,6 +936,7 @@ static void vfio_enable_msi(VFIODevice *vdev)
 
     for (i = 0; i < vdev->nr_vectors; i++) {
         VFIOMSIVector *vector = &vdev->msi_vectors[i];
+        MSIMessage msg = msi_get_message(&vdev->pdev, i);
 
         vector->vdev = vdev;
         vector->virq = -1;
@@ -951,13 +949,11 @@ static void vfio_enable_msi(VFIODevice *vdev)
         qemu_set_fd_handler(event_notifier_get_fd(&vector->interrupt),
                             vfio_msi_interrupt, NULL, vector);
 
-        vector->msg = msi_get_message(&vdev->pdev, i);
-
         /*
          * Attempt to enable route through KVM irqchip,
          * default to userspace handling if unavailable.
          */
-        vfio_add_kvm_msi_virq(vector, &vector->msg, false);
+        vfio_add_kvm_msi_virq(vector, &msg, false);
     }
 
     /* Set interrupt type prior to possible interrupts */